The Mars and Moon missions are primarily for planetary science but I'm wondering about Earth-focused projects.

One project that comes to mind was the failed Project Mohole. It spun off into the International Ocean Drilling Programme, which is a huge technical feat but isn't recognised outside the academic community. I'm sure they could attempt Mohole again with today's drilling tech if there was funding to it though.

The Landsat, Copernicus, and other earth observation satellite programs are incredibly useful in things like environmental monitoring and disaster relief but it's not really somthing that "pushes the envelope". Can we make it bigger?

Is there any scope in geosciences to for a massive, technically challenging project, or do the smaller regional-/university-level projects work better?